TWI615644B - High power fiber cladding energy remover - Google Patents

Description

High power fiber cladding energy remover

This invention relates to a device for eliminating unwanted light energy, and more particularly to a device for eliminating unwanted light energy using a diffraction effect.

Optical fiber is a transmission tool based on the principle of total reflection. Its raw material is mainly enamel. Because of its large surface reserves, the price of optical fiber is cheap. It has been widely used in applications such as today's social communication transmission, and is also widely used in medicine and entertainment. field.

High-power fiber laser is a small-volume laser system with convenient carrying and easy erection. It has high electro-optical conversion efficiency, good beam quality, and easy heat dissipation. It has been widely used in cutting, welding and hitting. Applications such as holes and surface treatments are the fastest growing laser products in the past decade, but high-power fiber lasers often have residual, redundant pump sources before the laser source output (output collimator). Energy, if the residual pump source energy is not removed, it will directly affect the beam quality of the output laser source, its beam quality will be worse, and excessive heat load will cause damage to the output collimator, and more, Residual laser light is reflected back to the laser system via the reflections produced by the output collimator, causing damage to the overall system.

A solution to the above problems involves a high refractive index glue Method: Generally, the passive double-clad fiber structure is composed of a fiber core, and an inner and outer cladding. The high refractive index glue method is in a passive double-clad fiber structure. The surface of the inner cladding layer is coated with a polymer gel material having a refractive index equal to or greater than the refractive index of the inner cladding material. The working principle of the method is mainly to regenerate the pump light in the cladding layer. Through the optical refraction effect and the scattering effect, the residual pump light is led out to the inner cladding layer, and the light is converted into heat by the gel material absorption and heat dissipation packaging mechanism design, and finally the air is cooled by air cooling or water cooling. Walking, to achieve the purpose of energy removal of the residual coating; however, the residual scattered light derived by this method will cause the temperature of the polymer gel-like material to rise, and the general polymer gel-like material can withstand the temperature at 90-100 degrees, the temperature When it is more than 150 degrees, the polymer gel material will burn out, so this method can handle the residual pump light energy of about 100W. This method is not suitable for multi-kilowatt fiber laser systems.

Therefore, there is a great need in the industry to develop a high-power fiber-clad energy remover, a heat-dissipating mechanism with good heat dissipation efficiency to provide a high-power laser to eliminate residual residual pump source energy before the output collimator, thus, At the same time, it can combine the quality and efficiency of laser light to avoid the reflection of residual laser light through the output collimator, which will cause damage to the overall system.

In view of the above disadvantages of the prior art, the main object of the present invention is to provide a high power fiber cladding energy remover, integrating a core unit, a cladding layer, a grating structure and a jacket to effectively control light energy. It also avoids the reflection of residual laser light via the output collimator to obtain a high quality laser beam.

In order to achieve the above object, according to one aspect of the present invention, a high power fiber cladding energy remover is provided, comprising: a core unit which is a light conducting material; and a cladding layer disposed outside the core unit The refractive index of the cladding layer is smaller than the refractive index of the core unit; a grating structure is disposed outside the cladding layer for generating a diffraction phenomenon; a jacket covering the core unit, the cladding layer, The grating structure is used to provide a protection function.

The grating structure may be prepared by one of a method such as a reticle lithography method, a two-beam interference technique, and a laser direct writing technique, and the grating structure may be a non-periodically arranged grating structure, or A periodically arranged grating structure may also be a periodically arranged tapered grating structure having a periodic change of its arrangement period; the grating structure has the following characteristics: the duty ratio of the grating structure can be designed to be 5%-95%. (duty ratio: grating cylinder width / grating spacing), the grating structure height may range from 0.5 μm to 200 μm, and the grating structure refractive index may range from 1.3 to 1.7, wherein the periodic grating structure, the tapered grating structure The period of the cycle may be from 0.5 μm to 3 μm.

The high power fiber cladding energy remover of the invention can be applied to a general fiber structure or a graded fiber structure, and the core unit can be composed of high refractive index glass, and the cladding layer can be made of a refractive index lower than the core. The material of the refractive index of the unit is composed of.

The above summary and the following detailed description and drawings are intended to further illustrate the manner, means and effects of the present invention in achieving its intended purpose. Other purposes and advantages of this creation will be explained in the following description and drawings.

110‧‧‧ core unit

120‧‧‧Cladding

130‧‧‧Grating structure

140‧‧‧ coat

150‧‧‧Excess pump source energy

160‧‧‧Diffractive light

The first figure is a schematic diagram of a high power fiber cladding energy remover according to the present invention; the second figure is a periodic grating structure diffraction efficiency versus periodic grating structure of a high power fiber cladding energy remover of the present invention. The refractive index is plotted; the third figure is a schematic diagram of the diffraction efficiency of a high power gradual fiber cladding energy remover of the present invention.

The embodiments of the present invention are described by way of specific examples, and those skilled in the art can readily understand the advantages and effects of the present invention from the disclosure of the present disclosure.

The invention designs a grating structure on the surface of the cladding layer of the optical fiber by the diffraction phenomenon of the grating, and can further process the residual pump light energy according to the prior art. The architecture of the invention is designed to set the grating structure on the optical fiber. The surface of the inner cladding layer is used to extract the residual pump source energy into the cladding layer by the diffraction principle of the periodic or non-periodic grating structure, and the pump source energy is injected into the heat dissipation mechanism to remove the residual Cladding pump source energy In addition, by the grating structure controlling the grating diffraction efficiency, the residual pump light energy is effectively and uniformly dispersed in a gradual manner, so that the dispersed energy is controlled in the micro-nano grating structure material. Below the sustainable power, the material withstand power problem faced by the high refractive index method can be solved.

Please refer to the first figure, which is a schematic diagram of a high power fiber cladding energy remover of the present invention. As shown in the figure, the present invention provides a high power fiber cladding energy remover comprising: a core unit 110 which is a light conducting material, the material is composed of high refractive index glass; a cladding layer 120, An outer surface of the core unit, the refractive index of the cladding layer is smaller than the refractive index of the core unit; a grating structure 130 disposed outside the cladding layer for generating a diffraction phenomenon; a jacket 140 covering the The core unit, the cladding layer, and the grating structure are used to provide a protection function. When the pump source energy enters the fiber, the excess pump source energy 150 is transmitted in the cladding layer. When the pump source energy is incident on the grating structure, the diffracted light 160 is formed by the diffraction phenomenon, and the excess pump source energy is derived to be removed. The residual cladding pumps the source energy for the purpose.

Example

Please refer to the second figure, which is a schematic diagram of the diffraction efficiency of the periodic grating structure of the high power fiber cladding energy remover of the present invention. As shown in the figure, in this embodiment, a periodic grating structure 130 is disposed on the surface of the inner cladding of the optical fiber, and the diameters of the optical fiber core (core unit 110), the cladding layer 120, and the outer sleeve 140 are respectively 20μm, 400μm and 550μm, refractive index of 1.447, 1.446 and 1.371, respectively, numerical apertures of 0.06 and 0.46, respectively, designed in this embodiment The grating structure 130 (grating) parameters are as follows: a period of 1.1 μm, a duty cycle of 50%, a structure depth of 13 μm, and a periodic grating structure 130 refractive index range of 1.3-1.6, which can be found when a periodic grating structure When the refractive index of 130 is larger than the refractive index of the outer casing 140, diffraction efficiency is generated, and when the refractive index is 1.54, the maximum diffraction efficiency is generated, which is about 68.5%.

Please refer to the third figure, which is a schematic diagram of the diffraction efficiency of a high power gradual fiber cladding energy remover according to the present invention. As shown in the figure, in this embodiment, a high-power gradual fiber cladding energy remover is prepared by grading the refractive index of the periodic grating structure. In this embodiment, the refractive index of the periodic grating structure is high. The power graded fiber cladding energy remover is formed by connecting a low diffraction efficiency to a high diffraction efficiency, and is divided into four segments, each segment having a length of 2 cm, and the refractive indices of the first segment to the fourth segment are 1.37 and 1.40, respectively. , 1.43 and 1.53, the calculated diffraction efficiencies are 18.5%, 27.0%, 39.7%, and 58.8%, respectively, calculated from the cladding energy of 400W, and the power that can be removed in each segment is 74.0(W). 8,8.0 (W), 94.4 (W), and 84.4 (W), the total removal power is up to 340.8 (W), the remaining power is 59.2 (W), can be removed by a general output collimator, or can be matched The high-break rate adhesive coating removes the components for removal. Therefore, in this embodiment, the power of each segment can be uniformly controlled within 100 (W) to achieve the purpose of average dispersion and removal of power.

The invention can use the reticle lithography method, the double beam interference technique, or the laser direct writing technology to prepare a periodic and non-periodic grating structure on the surface of the cladding layer of the optical fiber to generate a diffraction effect, and derive a redundant Light energy, In the diffraction efficiency control, the process parameters such as the exposure time are used to control the refractive index of the periodic grating structure, and the refractive index of the periodic grating structure can be controlled by controlling different micro-nano structure parameters, for example: Cycle, structure depth, duty cycle, mixed periodic structure, etc., or the material selection of the micro-nano grating structure can also be used to control the refractive index of the periodic grating structure, such as negative withstand power and high melting point The photoresist material (SU8 negative photoresist) has a withstand power density and temperature of about 80 (W) and 150 degrees per centimeter, respectively, or a micronano grating structure is fabricated on the optical fiber by means of a fiber-supported hydrogen.

The above-described embodiments are merely illustrative of the features and functions of the present invention and are not intended to limit the scope of the technical content of the present invention. Any person skilled in the art can modify and change the above embodiments without departing from the spirit and scope of the creation. Therefore, the scope of protection of this creation should be as The scope of the patent application described later is listed.

110‧‧‧ core unit

120‧‧‧Cladding

130‧‧‧Grating structure

140‧‧‧ coat

150‧‧‧Excess pump source energy

160‧‧‧Diffractive light

Claims (9)

A high power fiber cladding energy remover comprises: a core unit which is a light conducting material; a cladding layer disposed outside the core unit, the cladding layer having a refractive index smaller than a refractive index of the core unit a grating structure disposed outside the cladding layer for generating a diffraction phenomenon; a jacket covering the core unit, the cladding layer, and the grating structure for providing a protection function. The high power fiber cladding energy remover according to claim 1, wherein the grating structure is prepared by one of a reticle lithography method, a two-beam interference technique, and a laser direct writing technique. The high power fiber cladding energy remover of claim 1, wherein the grating structure is a non-periodically arranged grating structure. The high power fiber cladding energy remover of claim 1, wherein the grating structure is a periodically arranged grating structure or a periodic array of tapered grating structures. The high power fiber cladding energy remover of claim 4, wherein the periodic grating structure and the graded grating structure have a period ranging from 0.5 μm to 3 μm. The high power fiber cladding energy remover of claim 1, wherein the grating structure has a duty cycle ranging from 5% to 95%. The high power fiber cladding energy remover of claim 1, wherein the grating structure has a height ranging from 0.5 μm to 200 μm. The high power fiber cladding energy remover of claim 1, wherein the grating structure has a refractive index ranging from 1.3 to 1.7. The high power fiber cladding energy remover of claim 1, wherein the core unit is composed of high refractive index glass.